Social anxiety disorder - defined by a pervasive fear of social interactions - is associated with several cognitive distortions that facilitate the disorder. The broad objective of the proposed research is to evaluate self-regulatory depletion as one mechanism underlying the cognitive concomitants of social anxiety. It is contended that social interactions require a great deal of vigilance for the socially anxious, which depletes their self-regulatory system. Without sufficient self-regulatory resources, the socially anxious are vulnerable to cognitive distortions like over-attention to social threats and rumination. Five studies are proposed to examine two specific aims. The first aim is to demonstrate that self-regulatory depletion occurs in the socially anxious following social interaction. Study 1 will assess the general relationship between social anxiety and depletion. It is expected to show that, in the absence of social interaction, the socially anxious have comparable self-regulatory systems to non-anxious controls. Study 2 will measure self-regulatory among participants with a diagnosis of social phobia and among non-anxious controls. This study will also manipulate whether the participants have engaged in a social interaction. Study 3 uses a group interaction paradigm to assess whether interaction partners can perceive self-regulatory depletion in the socially anxious. The second aim is to demonstrate that self-regulatory depletion mediates the relationship between social anxiety and distortions in post-interaction processing. Study 4 will analyze the latency times of socially anxious and non-anxious controls when they interpret the meaning of a series of homographs (i.e., words that have multiple meanings). Finally, Study 5 will use a naturalistic methodology to assess whether self-regulatory depletion following social interactions promotes rumination among the socially anxious. Social anxiety disorder is a growing concern for public health because of the burden it places on both sufferers and the managed care system as a whole. The present research explores self-regulatory depletion (i.e., mental fatigue) as one explanation for negative thought processes that underlie social anxiety. It is expected that this research will expand understanding of social anxiety and inform future treatment models. [unreadable] [unreadable] [unreadable]